The present invention relates to a vehicle chassis frame with door openings having closure panels which become part of the frame when closed. In its more particular aspects, the invention is concerned with a frame construction wherein barrier sections of the frame extend upwardly to either side of the door openings and the door panels move within the confines of the frame between retracted positions beneath the floor of the frame and closed positions engaged between the barrier sections to impart tensile, compressive and torsional rigidity to the frame.
The invention is also concerned with an improved chassis frame for wheeled motor vehicles which provides a floor section between the door openings of a width significantly less than the width of the vehicle. The mid-portion of floor section is of an expanded vertical cross-section to impart rigidity to the frame and the edge portions of the frame are of a narrow vertical cross-section to accommodate the passage of rotatively mounted doors beneath the floor section.
In the prior art it is well known to provide vehicle chassis with door panels which move through a generally arcuate path between a stowed condition beneath the floor of the vehicle and a closed condition in a door opening. These door panels are generally of relatively conventional construction and do not cooperate with frame members of the vehicle chassis to impart significant torsional or compressive rigidity to the chassis. In some instances, the door panels are highly flexible and of a segmented or accordion-like structure which is incapable of sustaining torsional loads. In most instances, the door panels have been provided for closure purposes only and engage the body of the vehicle only for purposes of their own support and to affect a secure closure.
The prior art also teaches providing vehicles with conventional swinging door panels having latch structures which hold the panels in compression when closed and longitudinal beams which reinforce the panels against lateral impact. Although such door panels necessarily provide some reinforcement to the vehicle chassis, they do not provide frame structure which adds significantly to the torsional rigidity of the chassis by essentially eliminating the void in the chassis provided by the door opening.
Prior art vehicle chassis frames generally have relatively thick sills beneath the door openings. These sills serve as principal frame members and are spaced apart laterally of the chassis frame to the greatest extent permitted by the aesthetic design constraints of the vehicle. In some instances, particularly with convertible-type vehicles which do not have top structure, the sills comprise very deep frame structures which provide a substantial part of the torsional rigidity of the chassis frame.